1. Field Of The Invention
This invention relates to an automatic car-speed controller used for controlling the traveling speed of a car at a set point automatically.
2. Description Of The Prior Art
Heretofore, there have been many types of such automatic car-speed controllers. Among them, there has been an automatic car-speed controller provided with a car-speed sensor for outputting operating data proportional to an actual car-speed, an actuator for driving a throttle and a command switch for outputting a cruise command signal on outside of a microcomputer, and housed with a car-speed memorizing means for memorizing the operating data of said car-speed sensor in response to an operation of said command switch and a control means for giving a command to said actuator corresponding to a difference between actual car-speed and memorized car-speed in said microcomputer (Japanese Patent Disclosure No. 59-8023/84).
In said automatic car-speed controller, the memorizing means memorizes the car-speed at the time of OFF-operation by setting off the command switch subsequent to the ON-operation, the control means in the microcomputer gives the command to the actuator corresponding to the difference between actual car-speed and memorized car-speed. The throttle is driven according to the working of the actuator and the actual car-speed is controlled to the car-speed so as to travel at a constant traveling speed. Upon operating a brake pedal at the time of traveling at a constant traveling speed, current is cut off to the actuator and simultaneously a cancelling signal given by operating said brake pedal is input to the control means, and said control means cancels the car-speed controlling state, the actuator is changed to the nonworking state by a cancelling command from the control means and the system is cancelled.
However, in the conventional automatic car-speed controller described above, because the control means in the microcomputer makes the actuator into the nonworking state by the cancelling signal according to the operation of the brake pedal in case of cancelling the system by operating said brake pedal, there is the possibility that the car-speed controlling state can not be cancelled even if the current is cut off to the actuator by operating the brake pedal in the case of trouble in the microcomputer. Therefore there is a problem in that the actuator may return to the car-speed controlling state and drive the throttle so as to regulate the speed into the constant traveling speed memorized before the braking operation when the operation of the brake pedal is discontinued subsequent to the braking operation.